An Experimental Study of the Hydrodynamic Drag Coefficient of a Cooled Hard Sphere at Small Reynolds Numbers

A new method for the experimental study of gravitational sedimentation of a polydisperse cluster of solid spherical particles in a viscous fluid is presented. The method is based on the preliminary ultrasonic mixing of the particles in a spherical container and assumes the introduction of a spherical cluster of particles at a given concentration and zero initial velocity into a fluid. This method is used to determine sedimentation characteristics of a bidisperse cluster of particles (steel balls, 2 and 3 mm in diameter) in silicone oil. A qualitative pattern of the cluster evolution, a sedimentation rate, and a drag coefficient are obtained. A comparative analysis of sedimentation characteristics of monodisperse and bidisperse particle clusters is carried out in the range of Reynolds numbers Re = (0.30÷0.66)·10−3. It is shown that, in contrast to a monodisperse cluster of particles, the drag coefficient of the bidisperse cluster of particles does not correspond to a correlation CD = 24/Rec for the Stokes sedimentation.

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A Numerical and Experimental Study of the Aerodynamics and Stability of a Horizontal Parachute

ISRN Aerospace Engineering ◽

10.1155/2013/320563 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Mazyar Dawoodian ◽

Abdolrahman Dadvand ◽

Amir Hassanzadeh

Keyword(s):

Experimental Study ◽

Reynolds Number ◽

Numerical Simulations ◽

Drag Coefficient ◽

Reynolds Numbers ◽

Flow Conditions ◽

High Reynolds Numbers ◽

High Reynolds ◽

The Stability ◽

Good Agreement

The flow past a parachute with and without a vent hole at the top is studied both experimentally and numerically. The effects of Reynolds number and vent ratio on the flow behaviour as well as on the drag coefficient are examined. The experiments were carried out under free-flow conditions. In the numerical simulations, the flow was considered as unsteady and turbulent and was modelled using the standard - turbulence model. The experimental results reveal good agreement with the numerical ones. In both the experiments and numerical simulations, the Reynolds number was varied from 85539 to 357250 and the vent ratio was increased from zero to 20%. The results show that the drag coefficient decreases by increasing the Reynolds number for all the cases tested. In addition, it was found that at low and high Reynolds numbers, the parachutes, respectively, with 4% vent ratio and without vent are deemed more efficient. One important result of the present work is related to the effect of vent ratio on the stability of the parachute.

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The investigation of the height effect of a slit microchannel with a textured wall on its hydrodynamic drag

Journal of Physics Conference Series ◽

10.1088/1742-6596/2119/1/012050 ◽

2021 ◽

Vol 2119 (1) ◽

pp. 012050

Author(s):

A S Lobasov ◽

A V Minakov

Keyword(s):

Reynolds Number ◽

Pressure Drop ◽

Drag Coefficient ◽

Slip Length ◽

Reynolds Numbers ◽

Hydrodynamic Drag ◽

Channel Height ◽

Relative Pressure ◽

Effective Slip Length ◽

Effective Slip

Abstract The numerical investigation of the fluid flow in a slit microchannel with a textured wall was carried out. The effect of the channel height on the hydrodynamic drag coefficient, as well as on the pressure drop in such channel and the effective slip length on the wall for various Reynolds numbers, are presented in the paper. The channel length was 100 µm, and its height was varied from 25 µm to 500 µm. The Reynolds number was varied from 0.1 to 100. The main studied characteristics were compared to the similar ones obtained for a channel with normal walls (no-slip conditions). It was found that the pressure drop in such textured microchannel was lower as compared to a conventional channel for any of its heights and for any Reynolds numbers. The dependences of the relative pressure drop, effective slip length, and drag coefficient on the Reynolds number were obtained for different channel heights. The drag coefficient was described as 20/Re for the average values of the channel height. A correlation that describes the dependence of the friction factor on the Reynolds number for small and large heights of the channel was proposed. The accuracy of the proposed correlation was about 90%.

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Экспериментальное исследование коэффициента гидродинамического сопротивления охлажденной твердой сферы при малых числах Рейнольдса

Письма в журнал технической физики ◽

10.21883/pjtf.2021.07.50800.18592 ◽

2021 ◽

Vol 47 (7) ◽

pp. 46

Author(s):

В.А. Архипов ◽

С.А. Басалаев ◽

К.Г. Перфильева ◽

С.Н. Поленчук ◽

А.С. Усанина

Keyword(s):

Viscous Fluid ◽

Drag Coefficient ◽

Spherical Particle ◽

Temperature Difference ◽

Sedimentation Rate ◽

Silicone Oil ◽

Reynolds Numbers ◽

Hydrodynamic Drag ◽

Gravitational Sedimentation

The results of experimental studying the gravitational sedimentation of a cooled solid spherical particle in a viscous fluid in the range of Reynolds numbers Re = 0.01÷1.32 are presented. A significant decrease of stationary sedimentation rate (up to 30%) of a cooled particle is shown. Empirical dependencies for the sedimentation rate and hydrodynamic drag coefficient of the particle in the range of temperature difference between liquid (glycerol, silicone oil) and particle ∆T = (0÷210) K are obtained.

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Pulsatile pipe flow pseudoplastic materials; The flow enhancement for Re ≪ 1

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19831579 ◽

1983 ◽

Vol 48 (6) ◽

pp. 1579-1587 ◽

Cited By ~ 1

Author(s):

Ondřej Wein

Keyword(s):

Small Parameter ◽

Pipe Flow ◽

Quantitative Estimation ◽

Reynolds Numbers ◽

Power Law Model ◽

Viscosity Function ◽

Small Reynolds Numbers ◽

Title Problem ◽

Flow Enhancement ◽

Method Of Small Parameter

Solution of the title problem for the power-law model of viscosity function is constructed by the method of small parameter in the region of small Reynolds numbers. The main result of the paper is a quantitative estimation of the values of Re, when the influence of inertia on flow enhancement may be quite neglected.

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